Radojica Djokovic

Influence of lipolysis and ketogenesis to metabolic and hematological parameters in dairy cows during periparturient period.

The aim of this study was to examine the characteristics of the metabolic profile and complete blood count in cows in the periparturient period on the basis of the intensity of lipolysis and ketogenesis (concentration of non esterified fatty acid - NEFA and betahydroxybutyrate - BHB). Based on median values of NEFA and BHB cows were divided into 3 groups: cows physiologically burdened with catabolism (NEFA and BHB levels above the median one week after parturition), cows significantly burdened with catabolism (NEFA and BHB levels above the median one week before and after parturition) and cows that are not burdened with catabolism (NEFA and BHB below the median, i.e. the control group). The median value of NEFA was 0.27 mmol/L one week before parturition and 0.61 mmol/L one week after it. The median value of BHB was 0.51 mmol/L one week before parturition and 0.99 mmol/L one week after it. A significant group effect was shown for each week separately, so that cows physiologically burdened with catabolism and/or cows significantly burdened with catabolism compared to the control group have the following features of the metabolic profile and complete blood count: higher concentrations of NEFA and BHB (weeks: -1, 1, 2, 4, 8), lower concentrations of glucose (weeks: 1, 4), lower concentration of cholesterol (week 8), lower concentrations of total protein (weeks: 1, 2), lower concentrations of urea (weeks: 1, 2, 4, 8) and a higher concentration of bilirubin (weeks: - 1, 1, 2, 4, 8), increased levels of AST (weeks: -1, 1) and ALT (weeks: -1, 2), lower value of Ca (week -1), lower hemoglobin concentration (week -1), lower white blood cell count (week 4), a larger number of neutrophils (weeks: -1, 1, 2) and a higher number of lymphocytes (week 4). Using the method of factor analysis and principal components showed that NEFA, BHB and glucose are the major components that affect the metabolic profile and blood count, making 71.8% of the variability of all parameters. Cows with hypoglycemia, hypocalcemia, hypoalbuminemia, hyperbilirubinemia, decreased hemoglobin concentration and/or red blood cell count and neutrophil to lymphocyte ratio >1 showed significantly higher concentrations of NEFA and BHB compared to cows with parameters within normal ranges. Complete ROC (receiver operating characteristics) analysis showed that NEFA and BHB are important diagnostic indicators that allow the separation of cows with parameters out of the reference values from cows with normal values of parameters in the metabolic profile and blood count (0.5<AUC<0.87). Reliability of identification of cows with parameters that are out of the reference value increases with increasing concentrations of NEFA and BHB, which confirms that intense lipolysis and ketogenesis start a series of compensatory processes in the metabolism in cows. The results confirm that NEFA and BHB significantly affect the value of numerous metabolic and hematological parameters in the periparturient period. [Projekat Ministarstva nauke Republike Srbije, br. TR31062]

Bovine respiratory disease complex (BRDC): viral and bacterial pathogens in Serbia.

Pathogens causing BRDC in Serbia were investigated. Two herds of beef cattle with bovine respiratory disease were included, with twenty diseased calves (10 from each farm) were chosen for isolation of bacteria on artificial culture media and determination by aerobic cultivation. The most common bacterial pathogen was isolated was Pasteurella multocida. Diffusion method of sensitivity to antibiotics (antibiogram), revealed that Enrofloxacin and Floron were most efficient antibiotics against Pasteurella multocida isolates (100 % isolates sensitive on both antibiotics). From the all examined samples (n=20) using the method of Real Time PCR (RT-PCR and PCR) we determined the genome sequences of bovine respiratory syncytial virus (BRSV), but in none of the samples genome of bovine viral diarrhea virus (BVDV) and bovine herpesvirus-1 (BoHV-1). [Projekat Ministarstva nauke Republike Srbije, br. TR 31001]

Relationship between the indexes of insulin resistance and metabolic status in dairy cows during early lactation

Abstract Insulin resistance is a phenomenon which accompanies the ongoing metabolic adaptation in cows during early lactation. The aim of our study was to determine the linear correlations of HOMA (Homeostatic Model Assessment), QUICKI (Quantitative Insulin Sensitivity Check Index) and RQUICKI (Revised Quantitative Insulin Sensitivity Check Index) indexes of insulin resistance with the metabolic status of cows (concentration of hormones, metabolites and body condition score). The experiment included 40 Holstein-Frisian cows in the first week after calving. Indexes of insulin resistance valued: 18.68±5.43 (HOMA), 0.39±0.06 (QUICKI) and 0.45±0.06 (RQUICKI). Linear correlations were examined by testing the coefficient of correlation (r), determination (r2,%) and regression parameter beta (b) in linear equation. A negative correlation was found between HOMA and IGF-I (insulin growth factor I) (r=−0.51, r2=25.0, b=−1.1257, p<0.01). HOMA showed a positive correlation with BHB (betahidroxybutyrate) (r=0.48, r2=23.2, b=0.0234, p<0.01). A positive correlation was found between QUICKI and IGF-I (r=0.30, r2=10.0 b=46.7900, p<0.05) and cholesterol (r=0.44, r2=18.3, b=1.9021, p<0.01). In contrast, QUICKI and BHB (r=0.51, r2=27.1, b=−1.7241, p<0.01), just like QUICKI and BCS (r=0.46, r2=20.9, b=−2.424, p<0.01), showed a negative correlation. RQUICKI showed positive correlations with IGF-I (r=0.48, r2=22.8, b=28.1230, p<0.01), T4 (r=0.47, r2=22.1, b=87.142, p<0.01) and triglycerides (r=0.36, r2=13, b=0.0407, p<0.05) but negative correlations with cortisol (r=−0.36, r2=13.0, b=−9.0332, p<0.05), STH (somatotropic hormone) (r=−0.42, r2=17.3, b=−5.4976, p<0.01), BHB (r=−0.62, r2=38.3, b=−1.1872, p<0.01), total bilirubin (r=−0.58, r2=33.7, b=−7.131, p<0.01) and BCS (body condition score) (r=−0.6, r2=36.4, b=−1.8347, p<0.01). In conclusion, indexes of insulin resistance may be used to evaluate the metabolic status of cows in early lactation. RQUICKI might be the most appropriate predictor of metabolic status due to its linear relationship with most of the parameters included in homeorhetic process.

Investigation of bovine viral diarrhea virus (BVDV) and border disease virus (BDV) infections of sheep in Southwestern Serbia.

Serological assay (virus neutralization test - VNT) was employed to examine blood sera collected from sheep of different age categories reared under different housing systems for the presence of bovine viral diarrhea virus (BVDV) and Border disease virus (BDV) infections in sheep. The objective of the investigation in sheep as reservoir hosts of the viruses was to clarify the potential for their transmission to cattle herds and vice versa. Experimental Group A included 5 mini farms composed entirely of sheep that were not in cohabitation with cattle in the same buildings or on the same pasture. Experimental Group B was made up of five mini sheep farms, whose owners raised cattle as well. A total of 10 blood samples (5 from junior categories of sheep aged up to 12 months and 5 from the older sheep) were secured from each of the 10 mini farms selected for the study. The VNT method did not detect the presence of specific anti-BVDV antibodies to both BVDV genotypes (BVDV-1 and BVDV-2) in any of the 100 test blood serum samples of sheep. Specific anti-BDV antibodies to the BDV Moredun strain were not found in any of the test serum samples of 100 sheep.